Abstract

The published fragment anisotropy data in the fission of 209Bi induced by 23-140 MeV 4He ions are analyzed to deduce lcrit for different bombarding energies. These values of lcrit are found to be significantly lower than the optical model values of lmax at higher bombarding energies. The theoretical values of lcrit based on trajectory calculations with proximity potential and one body friction formalism are seen to agree with the experimentally deduced values. The significance of the above analysis for alternative experimental determination of 4He ion fusion (compound nucleus formation) cross section through deduction of lcrit is also pointed out.